title: Biomechanical variables associated with Achilles tendinopathy in runners.
abstract: OBJECTIVE
  The aim of this study was to investigate the kinetics, kinematics and muscle activity in runners with Achilles tendinopathy.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Biomechanics laboratory.
  
  
  METHODS
  21 runners free from injury and 21 runners with Achilles tendinopathy performed 10 running trials with standardised running shoes. Injured runners were diagnosed clinically according to established diagnostic criteria. Uninjured runners had been injury-free for at least 2 years.
  
  
  METHODS
  During each trial, kinetic and lower limb kinematic data were measured using a strain gauge force plate and six infrared cameras respectively. Electromyographic (EMG) data from six muscles (tibialis anterior (TA), peroneus longus (PE), lateral gastrocnemius (LG), rectus femoris (RF), biceps femoris (BF) and gluteus medius (GM)) were measured with a telemetric EMG system.
  
  
  RESULTS
  Knee range of motion (heel strike to midstance) was significantly lower in injured runners than in uninjured runners. Similarly, preactivation (integrated EMG (IEMG) in 100 ms before heel strike) of TA was lower for injured runners than uninjured runners. RF and GM IEMG activity 100 ms after heel strike was also lower in the injured group. However, impact forces were not different between the two groups.
  
  
  CONCLUSIONS
  Altered knee kinematics and reduced muscle activity are associated with Achilles tendinopathy in runners. Rehabilitation exercises or other mechanisms (e.g. footwear) that affect kinematics and muscle activity may therefore be beneficial in the treatment of runners with Achilles tendinopathy.
authors.affiliation: Institute of Sports and Exercise Science, University of Worcester, Worcester, UK. l.azevedo@tees.ac.uk
authors.forename: L B
authors.initials: LB
authors.lastname: Azevedo
authors.forename: M I
authors.initials: MI
authors.lastname: Lambert
authors.forename: C L
authors.initials: CL
authors.lastname: Vaughan
authors.forename: C M
authors.initials: CM
authors.lastname: O'Connor
authors.forename: M P
authors.initials: MP
authors.lastname: Schwellnus
mesh_terms: D000125:Achilles Tendon / Q000293:injuries / Q000503:physiopathology*; D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D016022:Case-Control Studies; D004576:Electromyography; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D012420:Running / Q000293:injuries / Q000502:physiology*; D052256:Tendinopathy / Q000503:physiopathology* / Q000534:rehabilitation